This invention relates in general to converters for converting synchro or resolver outputs into digital or dc outputs and more particularly relates to an improved input system of isolation transformers for such converters.
It is frequently necessary to convert the outputs of synchros or resolvers into digital signals or dc outputs. Such conversion can be accomplished by conventional demodulators and analog-to-digital converters. In making this conversion it is desirable to isolate the electronic components of the demodulator and converter from the resolver or synchro output. This elimates undesirable dc biases on the inputs to the demodulator or converter.
Present systems use isolation transformers to accomplish the isolation of the synchro or resolver output from the demodulator or converter input. These systems couple the resolver or synchro outputs directly to the primary windings of the isolation transformers. The voltage drops across the secondary windings, which are proportional to the synchro or resolver output voltages, are used as the inputs to operational amplifiers which apply a scale factor to generate output voltages which are fed to the demodulator or converter.
The isolation transformers used in these systems have many turns of thin wire in the windings. Such transformers are costly and may present reliability problems. These transformers also have special balancing requirements. In addition, the systems are not easily adaptable to different synchro or resolver output voltages. Finally, when these systems are used it is difficult to protect the converter from high voltage spikes.
In accordance with the present invention, the foregoing drawbacks and disadvantages are obviated and an improved system for isolating synchro and resolver outputs from converter and demodulator inputs is provided.